A small tree, rarely 20° high with a trunk 10′ in diameter, covered with pale bark, spreading branches forming a flat-topped head and slender terete pale gray branchlets; more often a many-stemmed shrub.
Distribution. Florida, in sandy soil on the Everglade Keys, Dade County, and on several of the southern keys; on the Bahamas and many of the Antilles; in Florida arborescent on Long Key in the Everglades, and on Big Pine Key.
XXVI. RUTACEÆ.
Trees or shrubs, abounding in a pungent or bitter aromatic volatile oil, with simple or compound usually glandular-punctate leaves, without stipules or rarely with stipular spines. Flowers regular, perfect or unisexual, in paniculate or corymbose cymes; calyx 3—5-lobed, the lobes more or less united at base, imbricated in the bud; petals 3—5, imbricated in the bud; stamens as many or twice as many as the petals; filaments distinct or united below; anthers introrse, 2-celled, the cells opening longitudinally; pistils 1—4, separate or united into a compound ovary sessile or stipitate on a glandular disk; styles mostly united; ovules usually 2 in each cell of the ovary, pendulous, anatropous or amphitropous; raphe ventral; micropyle superior. Fruit of 2-valved carpels, a samara, drupe or capsule. Seeds solitary or several; seed-coat bony or crustaceous, furrowed or punctate; embryo axile in fleshy albumen; radicle short, superior.
Of this large family, widely distributed over the warm and temperate parts of the earth’s surface, four genera only have arborescent representatives in the United States. Citrus Aurantium L., the Bitter-sweet Orange, a native of Asia, has long been naturalized in the peninsula of Florida, where other species of this genus have escaped from cultivation and are now growing spontaneously.
CONSPECTUS OF THE ARBORESCENT GENERA OF THE UNITED STATES.
Fruit of 1—5, 2-valved 1-seeded carpels; flowers diœcious or polygamous.1. [Xanthoxylum.] Fruit of 3 or 4-winged indehiscent 1-seeded carpels; flowers perfect.2. [Helietta.] Fruit a winged samara; flowers polygamous.3. [Ptelea.] Fruit a 1-seeded drupe; flowers perfect or polygamous.4. [Amyris.]
1. XANTHOXYLUM L.
Trees or shrubs, with acrid aromatic bark, pellucid aromatic-punctate fruit and foliage, scaly buds, and usually stipular spines. Leaves alternate, unequally or rarely equally pinnate; leaflets generally opposite, often oblique at the base, entire or crenulate. Flowers small, diœcious or polygamous, in axillary or terminal broad or contracted pedunculate cymes; calyx and petals hypogynous; disk small or obscure; stamens as many as the petals and alternate with them, hypogynous, effete, rudimentary or wanting in the female flower; filaments filiform or subulate; pistils 1—5, oblique, raised on the summit of a fleshy gynophore, connivent, sometimes slightly united below, rudimentary, simple or 2—5-parted in the sterile flower; ovaries 1-celled; styles short and slender, more or less united toward the summit; stigmas capitate; ovules collateral, pendulous from the inner angle of the cell. Fruit of 1—5 coriaceous or fleshy 1-seeded carpels, broad-obovoid, sessile or stipitate, ventrally dehiscent. Seed solitary oblong or globose, suspended on a slender funicle, often hanging from the carpel at maturity; seed-coat black, shining, conspicuously marked by the broad hilum; cotyledons oval or orbicular, foliaceous.
Xanthoxylum is widely distributed through tropical and extratropical regions and is most abundant in tropical America. It is represented in North America by one shrub and by four arborescent species of the southern states. The resin contained in the bark, especially in that of the roots, is a powerful stimulant and tonic occasionally used in medicine.